PRO FOOTBALL

PRO FOOTBALL; New Math: 12 Minus 10 Leaves 4

By GERALD ESKENAZI

Published: December 21, 1992

For the underground army that tries to figure out the arcane world of the National Football League's playoffs, yesterday was the day of days.

This much was certain (or so it seemed) on the next-to-last weekend of the regular season: Minnesota (without Herschel Walker) clinched the National Conference Central Division title by defeating Pittsburgh. Philadelphia (with Herschel Walker) guaranteed itself a wild-card playoff spot by defeating Washington. And Miami guaranteed another Don Shula appearance in the playoffs last night by defeating the Jets. These are solid, year-in, year-out playoff contenders.

More surprising was San Diego, which lost its first four games this season but became the first team to overcome that handicap and make the playoffs.

Miami's victory had other repercussions: Besides keeping alive Miami's chances for a division title, it simultaneously lifted Houston into the playoffs and eliminated overachieving Indianapolis.

Of the 12 playoff berths, 10 are filled with 4 teams left in contention for the other spots. Two of the four -- the Chiefs and the Broncos -- will meet in Kansas City next Sunday, with the winner getting the final wild-card berth in the American Conference playoffs. For the other two contenders, the Redskins and Packers, the outlook is more complicated. But one of them will end up with the final N.F.C. wild-card berth.

The Chargers, meanwhile, made sure they're in. They won their ninth game in 10 starts, routing the Raiders, to guarantee at least a wild-card playoff berth.

The Bills also did what they needed to do if they are to capture the American Conference East championship. But the playoff-bound Bills, after defeating the Saints, must wait another week to see if they finish first in the A.F.C. East and maintain home-field advantage in the playoffs.

No wonder there remained uncertainties that may not be resolved until next Sunday night. The East and West divisions of the A.F.C., as well as the N.F.C. East still does not have a champion.

But several clubs control their playoff prospects: The Chargers can win their division by defeating Seattle next Sunday, and Dallas can take the N.F.C. East with a victory tonight over Atlanta. A Week-Long Wait

All those real-life Senators and Washington power-brokers who come along for the ride whenever the Redskins make the playoffs will have to wait until the final Sunday of the regular season to determine their fate. Washington, which plays the Raiders on Saturday, can make the playoffs by winning -- or losing.

It makes perfect sense if you have three assistants with erasers on pencils or a calculator, or a friend at the N.F.L. who can slip you the information.

The secret is: tie breakers, various formulas to determine which of three 10-6 teams will actually qualify (it matters if two are from the same division, but that's another story).

But last night a cheerful math wizard in the N.F.L.'s office on Park Avenue assured the world that, indeed, the Redskins can make the playoffs but only if they don't wind up in a three-way tie with Philadelphia and Green Bay.

Simply, Washington -- the reigning Super Bowl champion -- is in if Green Bay loses to Minnesota on Sunday. In that scenario, it wouldn't matter if Washington had won on Saturday. If Green Bay wins, however, then Washington needs to have won, too -- and to have help from Philadelphia beating the Giants. If Philadelphia loses to the Giants it would create a three-way tie at 10-6 among Green Bay, Philadelphia and Washington and Green Bay would come out on top and the Redskins would be eliminated.

Why? Because the league says so. It comes down to Philadelphia eliminating Washington on the basis of a better record within the N.F.C. East. Colts' Wait Ends

And what about Indianapolis? The 8-7 Colts had a chance to become the first team in league history to progress from a one-victory season to the playoffs in consecutive years.

All they needed (besides help from the Jets last night) was to have defeated Cincinnati next week while the Dolphins lost again, to New England and Denver lost in Kansas City. There were too many if's.

Coach Rich Kotite of the Eagles was most likely in the same position as many of his colleagues throughout yesterday's long, nail-biting day.

"I was doing a lot of praying on the sideline at the end of the game," said Kotite. The game ended with Eric Allen deflecting a Mark Rypien pass in the end zone.

The Broncos' victory over the Seahawks -- keeping Denver alive in the playoff race -- also was sealed by batting away a last-second pass, this one thrown by Seattle's Stan Gelbaugh.

And then calculators were recharged, pencils sharpened, fans poised for the final game of the day in Miami, which was decided by a field goal with 7 seconds left.